A dual clutch transmission typically has dual input clutches or dual output clutches that are alternately engaged and disengaged in a slipping manner to alternate torque transferred from an input member to the different layshafts of the transmission as the transmission progresses through the available speed ratios. Such launch clutches have inherent heat and spin losses.
Single-motor hybrids usually require clutch-to-clutch shifts (i.e., shifts that involve energy losses) with associated spin losses and pump power requirements. Two-motor hybrid transmissions may allow synchronous shifts, but are typically expensive and difficult to package.